U.S. patent application number 10/603662 was filed with the patent office on 2004-02-26 for liquid crystal display device.
This patent application is currently assigned to LG.Philips LCD Co., Ltd.. Invention is credited to Chang, Youn Gyoung, Kim, Woong Kwon.
Application Number | 20040036815 10/603662 |
Document ID | / |
Family ID | 31884964 |
Filed Date | 2004-02-26 |
United States Patent
Application |
20040036815 |
Kind Code |
A1 |
Kim, Woong Kwon ; et
al. |
February 26, 2004 |
Liquid crystal display device
Abstract
A liquid crystal display device includes a plurality of gate
lines and data lines arranged horizontally and vertically,
respectively, for defining a plurality of pixel areas; a plurality
of switching devices formed at intersections of the gate lines and
the data lines; and a pixel electrode formed in a pixel area
connected to the switching device corresponding to the pixel area
and partially overlapping the data lines adjacent to the
corresponding pixel area, wherein a first parasitic capacitance
generated by the pixel electrode overlapping a data line for the
corresponding pixel area and a second parasitic capacitance
generated the pixel electrode overlapping a data line for an
adjacent pixel area are substantially equal to each other.
Inventors: |
Kim, Woong Kwon;
(Gyeonggi-Do, KR) ; Chang, Youn Gyoung;
(Gyeonggi-Do, KR) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
LG.Philips LCD Co., Ltd.
|
Family ID: |
31884964 |
Appl. No.: |
10/603662 |
Filed: |
June 26, 2003 |
Current U.S.
Class: |
349/38 |
Current CPC
Class: |
G02F 1/1362
20130101 |
Class at
Publication: |
349/38 |
International
Class: |
G02F 001/1343 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 22, 2002 |
KR |
49859/2002 |
Claims
What is claimed is:
1. A liquid crystal display device comprising: a plurality of gate
lines and data lines arranged horizontally and vertically,
respectively, for defining a plurality of pixel areas; a plurality
of switching devices formed at intersections of the gate lines and
the data lines; and a pixel electrode formed in a pixel area
connected to the switching device corresponding to the pixel area
and partially overlapping the data lines adjacent to the
corresponding pixel area, wherein a first parasitic capacitance
generated by the pixel electrode overlapping a data line for the
corresponding pixel area and a second parasitic capacitance
generated the pixel electrode overlapping a data line for an
adjacent pixel area are substantially equal to each other.
2. The liquid crystal display device according to claim 1, wherein
a part of the data line for the corresponding pixel area protrudes
into the corresponding pixel area and is overlapped by the pixel
electrode.
3. The liquid crystal display device according to claim 1, wherein
a part of the data line of the adjacent pixel area protrudes into
the corresponding pixel area and is overlapped by the pixel
electrode.
4. The liquid crystal display device according to claim 1, wherein
a portion of the pixel electrode overlapping a data line has a
taper shape.
5. The liquid crystal display device according to claim 1, wherein
a portion of the data line of the corresponding pixel area
protrudes into the corresponding pixel area and a portion of the
pixel electrode overlapping a data line for the adjacent pixel area
has a taper shape.
6. The liquid crystal display device according to claim 1, wherein
the switching devices are thin film transistors.
7. The liquid crystal display device according to claim 6, wherein
each of the thin film transistors comprises: a gate electrode
formed of a protrusion from the gate line; an insulating layer
deposited over an entire substrate on which the gate electrode is
formed; a semiconductor layer formed on the insulating layer;
source and drain electrodes formed on the semiconductor layer; and
a passivation layer deposited over the source and drain electrodes
and the semiconductor layer.
8. The liquid crystal display device according to claim 7, wherein
the source electrode protrudes into the pixel area and is
overlapped by the pixel electrode.
9. The liquid crystal display device according to claim 7, wherein
a portion of the pixel electrode protrudes and overlaps a source
electrode of a thin film transistor for the corresponding pixel
area.
10. The liquid crystal display device according to claim 1, further
comprising a storage capacitor electrode crossing the corresponding
pixel area in parallel to the gate line, wherein at least one of
the data lines adjacent to the corresponding pixel area has a
portion protruding under the pixel electrode and over the storage
capacitor electrode.
11. A liquid crystal display device comprising: a plurality of gate
lines and data lines arranged horizontally and vertically defining
a plurality of pixel areas; a plurality of switching devices formed
at intersections of the gate lines and the data lines; and a pixel
electrode formed in a pixel area connected to the switching device
corresponding the pixel area, each pixel electrode having a portion
with a taper shape overlapping a data line of an adjacent pixel
area, wherein a portion of the data line for the corresponding
pixel area protrudes into the corresponding pixel area such that a
first parasitic capacitance generated by the pixel electrode
overlapping a data line of the corresponding pixel area and a
second parasitic capacitance generated by the pixel electrode
overlapping the data line for the adjacent pixel area are
substantially equal to each other.
12. The liquid crystal display device according to claim 11,
wherein the switching devices are thin film transistors.
13. The liquid crystal display device according to claim 12,
wherein each of the thin film transistors comprises: a gate
electrode formed of a protrusion from the gate line; an insulating
layer deposited over an entire substrate on which the gate
electrode is formed; a semiconductor layer formed on the insulating
layer; source and drain electrodes formed on the semiconductor
layer; and a passivation layer deposited over the source and drain
electrodes and the semiconductor layer.
14. The liquid crystal display device according to claim 11,
further comprising a storage capacitor electrode crossing the
corresponding pixel area in parallel to a gate line, wherein at
least one of the data lines adjacent to the corresponding pixel
area have a portion protruding under the pixel electrode and over
the storage capacitor electrode.
15. A liquid crystal display device comprising: a plurality of gate
lines and data lines arranged horizontally and vertically,
repectively, for defining a plurality of pixel areas; a plurality
of switching devices formed at intersections of the gate lines and
the data lines; and a pixel electrode formed in a pixel area
connected to a switching device corresponding to the pixel area and
partially overlapping the data lines adjacent to the corresponding
pixel area, wherein a first area of a data line for the
corresponding pixel area overlapped with the pixel electrode and a
second area of a data line for an adjacent pixel area overlapped
with the pixel electrode are substantially equal to each other.
16. The liquid crystal display device according to claim 15,
wherein a part of the data line for the corresponding pixel area
protrudes into the corresponding pixel area and is overlapped by
the pixel electrode.
17. The liquid crystal display device according to claim 15,
wherein a portion of the pixel electrode overlapping a data line
has a taper shape.
18. The liquid crystal display device according to claim 15,
wherein a source electrode of the switching device protrudes into
the pixel area and is overlapped by the pixel electrode.
19. The liquid crystal display device according to claim 15,
wherein a portion of the pixel electrode protrudes and overlaps a
source electrode of a switching device for the corresponding pixel
area.
20. The liquid crystal display device according to claim 15,
further comprising a storage capacitor electrode crossing the
corresponding pixel area in parallel to a gate line, wherein at
least one of the data lines adjacent to the corresponding pixel
area have a portion protruding under the pixel electrode and over
the storage capacitor electrode.
Description
[0001] This application claims the benefit of Korean Application
No. 2002-49859 filed in Korea on Aug. 22, 2002, which is hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a liquid crystal display
device, and more particularly, to a liquid crystal display device
with improved picture quality and increased aperture ratio.
[0004] 2. Description of the Background Art
[0005] As the information society develops, displays becomes more
important as more information is transmitted via visual media. In
order for a display to be of practical use, a display has to have
low power consumption and high picture quality while being both
thin and light. A liquid crystal display (LCD) not only meets these
conditions but also can be mass produced such that new products
having a liquid crystal display device can be manufactured rapidly.
Thus, the liquid crystal display device is gradually taking the
place of the conventional cathode ray tube (CRT) in the visual
component industry.
[0006] The liquid crystal display device displays an image by using
an optical anisotropy of a liquid crystal. Typically, an active
matrix (AM) method of driving the display device by an active
device, such as a thin film transistor (TFT), is commonly used to
control the optical anisotropy of the liquid crystal. More
particularly, the liquid crystal display device comprises an upper
substrate including a color filter for displaying colors and a
black matrix for shielding light, a lower substrate including a
pixel area and a thin film transistor used a the active switching
device, and the liquid crystal positioned between the upper
substrate and the lower substrate.
[0007] FIG. 1 is a plan view of a related art liquid crystal
display device, which shows an array of pixels on the lower
substrate of the liquid crystal display device. As shown in FIG. 1,
each pixel is bounded by a gate line 10 and a data line 15. Each
pixel area contains a pixel electrode 20 formed adjacent to where
the gate line 10 and the data line 15 intersect each other. At the
intersection of the gate line 10 and the data line 15, a thin film
transistor 30 is positioned.
[0008] The thin film transistor 30 comprises a gate electrode 31
connected to the gate line 10, a source electrode 32 connected to
the data line 15, a drain electrode 33 connected to the pixel
electrode 20. In addition, the thin film transistor includes a gate
insulating layer (not shown) for insulating the gate electrode 31
and the source/drain electrodes 32 and 33, and a semiconductor
layer 34. A conductive channel is formed in the semiconductor layer
34 between the source electrode 32 and the drain electrode 33 when
a gate voltage is supplied to the gate electrode 31.
[0009] As shown in FIG. 1, a storage capacitor electrode 40 for
maintaining a pixel voltage is arranged in parallel to the gate
line 10 in each pixel area. In general, the pixel electrode 20 of
the lower substrate, the liquid crystal (not shown), and the common
electrode (not shown) of the upper substrate constitutes a liquid
crystal capacitor. However, a voltage applied to the liquid crystal
capacitor can not be maintained until a next signal is applied
because of leakage in the liquid crystal capacitor. Accordingly, in
order to maintain the applied voltage on the liquid crystal
capacitor, a storage capacitor has to be used with the liquid
crystal capacitor to maintain the applied voltage on the liquid
crystal capacitor. The storage capacitor not only maintains a
signal voltage but also stabilizes gray scale as well as reduces
flicker and after-image effect.
[0010] There are two methods of forming a storage capacitor. One
method is to form the storage capacitor electrode in addition to
the other electrodes and then connect the storage electrode to the
common electrode. The other method is to use a part of the
n-1.sup.th gate line as the storage capacitor electrode of the
n.sup.th pixel area. The former method is called storage on common
method or an independent storage capacitor method, and the latter
method is called storage on gate method or storage on previous gate
method.
[0011] The thin film transistor 30, the data line 15, and the
storage capacitor electrode 40 shown in FIG. 1 are formed of opaque
metal materials that lower an aperture ratio of the pixel area at
the time light is transmitted from a back light (not shown) through
the lower substrate. The pixel electrode is formed of a transparent
conductive material, such as Indium Tin Oxide. To improve the
aperture ratio, the pixel electrode is extended over the adjacent
data lines 15 and the portion of a black matrix that would be
overlapping the pixel electrode along the data line is removed.
[0012] FIG. 2 is a plan view showing a part of the liquid crystal
display device having a high aperture ratio in accordance with the
related art, as discussed above. As shown in FIG. 2, the n.sup.th
data line 15n and the n+1.sup.th data line 15n+1 are located in a
row direction, and the gate line 10 is formed in a column
direction. A part of the n+1.sup.th data line protrudes to form the
source electrode 32 of the thin film transistor 30. Also, in the
liquid crystal display device having a high aperture ratio, the
data lines 15n and 15n+1 are overlapped with a part of the pixel
electrode 21 in order to improve the aperture ratio. The
cross-hatched areas of S1 and S2 in FIG. 2 denote overlap areas
between the data lines 15n/15n+1 and the pixel electrode 21.
Because the pixel electrode 21 covers the entire pixel area bounded
by the data lines 15n/15n+1, the aperture ratio is increased.
[0013] In the related art liquid crystal display device having a
high aperture ratio, the data lines 15n and 15n+1 are overlapped
with the pixel electrode 21, a thus a parasitic capacitance
C.sub.dp is generated between the data lines 15n/15n+1 and the
pixel electrode 21. Also, as shown in FIG. 2, the pixel electrode
21 is not formed on the switching device 30, so that an area S1 in
which the pixel electrode 21 is overlapped with the n.sup.th data
line 15n is not equal to an area S2 in which the pixel electrode 21
is overlapped with the n+1.sup.th data line 15n+1. Accordingly, a
difference is generated between the parasitic capacitances of the
right and left sides of the pixel electrode. Such a difference
deteriorates the picture quality of the liquid crystal display
device. That is, even if the pixel electrode 21 is extended over
the data lines 15n and 15n+1 to improve the aperture ratio, a light
leakage phenomenon occurs at an edge of the pixel area at the time
the pixel is switched from "on" to "off" due to the difference of
the parasitic capacitances on the sides of the pixel electrode.
SUMMARY OF THE INVENTION
[0014] Accordingly, the present invention is directed to a
fabrication method of an LCD device that substantially obviates one
or more of the problems due to limitations and disadvantages of the
related art.
[0015] An object of the present invention is to provide a liquid
crystal display device which prevents deterioration of picture
quality generated at the time a pixel is switched from "on" to
"off".
[0016] Another object of the present invention is to provide a
liquid crystal display device having parasitic capacitances on the
right and left sides of the pixel electrode to be substantially
equivalent.
[0017] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described herein, there is provided a liquid crystal display device
including a plurality of gate lines and data lines arranged
horizontally and vertically, respectively, for defining a plurality
of pixel areas; a plurality of switching devices formed at
intersections of the gate lines and the data lines; and a pixel
electrode formed in a pixel area connected to the switching device
corresponding to the pixel area and partially overlapping the data
lines adjacent to the corresponding pixel area, wherein a first
parasitic capacitance generated by the pixel electrode overlapping
a data line for the corresponding pixel area and a second parasitic
capacitance generated the pixel electrode overlapping a data line
for an adjacent pixel area are substantially equal to each
other.
[0018] In another aspect, a liquid crystal display device includes
a plurality of gate lines and data lines arranged horizontally and
vertically defining a plurality of pixel areas; a plurality of
switching devices formed at intersections of the gate lines and the
data lines; and a pixel electrode formed in a pixel area connected
to the switching device corresponding the pixel area, each pixel
electrode having a portion with a taper shape overlapping a data
line of an adjacent pixel area, wherein a portion of the data line
for the corresponding pixel area protrudes into the corresponding
pixel area such that a first parasitic capacitance generated by the
pixel electrode overlapping a data line of the corresponding pixel
area and a second parasitic capacitance generated by the pixel
electrode overlapping the data line for the adjacent pixel area are
substantially equal to each other.
[0019] In another aspect, a liquid crystal display device includes
a plurality of gate lines and data lines arranged horizontally and
vertically, respectively, for defining a plurality of pixel areas;
a plurality of switching devices formed at intersections of the
gate lines and the data lines; and a pixel electrode formed in a
pixel area connected to a switching device corresponding to the
pixel area and partially overlapping the data lines adjacent to the
corresponding pixel area, wherein a first area of a data line for
the corresponding pixel area overlapped with the pixel electrode
and a second area of a data line for an adjacent pixel area
overlapped with the pixel electrode are substantially equal to each
other.
[0020] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention.
[0022] FIG. 1 is a plan view of a related art liquid crystal
display device, which shows an array of pixels on the lower
substrate of the related art liquid crystal display device.
[0023] FIG. 2 is a plan view showing a part of the liquid crystal
display device having a high aperture ratio in accordance with the
related art.
[0024] FIGS. 3A and 3B are plan views showing a pixel of a liquid
crystal display device according to a first embodiment of the
present invention.
[0025] FIGS. 4A and 4B are plan views showing a pixel of a liquid
crystal display device according to a second embodiment of the
present invention.
[0026] FIG. 5 is a plan view showing a pixel of a liquid crystal
display device according to a third embodiment of the present
invention.
[0027] FIG. 6 is a plan view showing a pixel of a liquid crystal
display device according to a fourth embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0029] The present invention provides a liquid crystal display
device of a high aperture ratio that prevents picture quality
deterioration by making parasitic capacitances generated at right
and left sides of a pixel electrode to be substantially equal to
each other. To make the parasitic capacitances generated at right
and left sides of the pixel electrode to be substantially equal to
each other such that light leakage does not occur, the structures
of a data line and/or a pixel electrode are altered by protruding
the data line into a pixel area or by configuring the pixel
electrode to protrude over a portion of the data line.
[0030] The parasitic capacitance formed between a data line and a
pixel electrode is determined by a following equation 1.
C.sub.dp=.epsilon.A/d [equation 1]
[0031] In equation 1, C.sub.dp denotes a parasitic capacitance
between the data line and the pixel electrode, A denotes an area of
an overlap between the pixel electrode and a data line, and d
denotes thickness of the dielectric, that is, a distance between
the overlapped data line and pixel electrode between which the
dielectric is positioned. The dielectric between the data line and
the pixel electrode is an insulator in which electric current does
not flow and has an intrinsic permittivity .epsilon..
[0032] The liquid crystal display device according to the present
invention prevents a picture quality deterioration due to the
parasitic capacitance difference by configuring areas where the
pixel electrode overlaps with the data lines located at right and
left sides of the pixel area to be substantially equal to each
other. The pattern of the data line and/or pixel electrode can be
configured to make the areas of the pixel electrode on both sides
of the pixel that overlap the data lines to be substantially equal.
Hereinafter, exemplary embodiments of the liquid crystal display
device according to the present invention will be explained with
reference to FIGS. 3 through 6. Throughout the explanations of the
exemplary embodiments, the n.sup.th data line will be defined as a
data line of a corresponding pixel area, and the n+1.sup.th data
line will be defined as a data line of an adjacent pixel area.
[0033] FIGS. 3 through 6 are exemplary embodiments of the liquid
crystal display device according to the present invention, in which
an array substrate corresponding to a lower substrate of a liquid
crystal display device is shown. In each of the respective FIGS. 3
through 6, the array substrate comprises: a plurality of gate lines
110, 210, 310, and 410 and data lines 115, 215, 315, and 415
arranged horizontally and vertically to define a pixel area; a
plurality of switching devices, such as thin film transistors 130,
230, 330, and 430 formed at intersections of the gate lines and the
data lines; and pixel electrodes 120, 220, 320, and 420 formed to
be partially overlapped with the data lines 115, 215, 315, and
415.
[0034] Each of the thin film transistors, such as 130, 230, 330 and
430 includes a gate electrode formed of a protrusion from a gate
line, such as gate lines 110, 210, 310 and 410. An insulating layer
(not shown) is deposited over the gate electrode on the lower
substrate. Then, a semiconductor layer (not shown) is formed on the
insulating layer. Subsequently, source/drain electrodes are formed
on the semiconductor layer and a passivation layer is deposited
over the source/drain electrodes and the semiconductor layer.
[0035] In each of the exemplary embodiments, overlapped areas of
the data lines and the pixel electrodes before structures of the
data lines and the pixel electrodes are configured are referred to
as areas S1 or S2, and overlapped areas of the data lines and the
pixel electrodes after structures of the data lines and/or the
pixel electrodes are configured are referred to as areas S1' or
S2'. Areas S1 and S1' are overlapped areas of the n.sup.th data
line and the pixel electrode. Areas S2 and S2' are overlapped areas
of the n+1.sup.th data line and the pixel electrode. To address
electric field affects in a liquid crystal arrangement at an edge
of the pixel area when the pixel electrode overlaps the data lines,
a width d1 in which the pixel electrode overlaps the nth data line
can have a different width than a width d2 in which the pixel
electrode is overlaps the n+1.sup.th data line. Therefore, the area
S1 can be larger than the area S2 or contrary to this, the area S2
can be larger than the area S1.
[0036] FIGS. 3A and 3B are plan views showing a pixel of a liquid
crystal display device according to a first embodiment of the
present invention. FIG. 3A shows a pattern of data lines 115n and
115n+1 in a case where area S1 would have been smaller than area S2
since width d1 is less than the width d2. As shown in FIG. 3A, a
source electrode 132 of a thin film transistor 130 of the
corresponding pixel area is formed in the data line 115n for the
corresponding pixel area to protrude into the corresponding pixel
area, thereby creating an increasing overlapped area S1'. The
increase is caused by the protrusion of the nth data line 115n
under the pixel electrode 120 of the corresponding pixel area. The
region A in FIG. 3A denotes the increase of the overlapped area S1'
such that area S1' is substantially equivalent to the area S2.
[0037] FIG. 3B shows a pattern of the data lines 115n and 115n+1
for a corresponding pixel area in a case where the area S1 would
have been larger than the area S2 since the width d1 is greater
than the width d2. In FIG. 3B, the data line 115n+1 for the
adjacent pixel area is patterned to protrude into the corresponding
pixel area as an oblique line, thereby increasing an overlapped
area S2' to be substantially equal to the area S1. The region B in
FIG. 3b denotes an increased overlapped area.
[0038] Any pattern of the data lines 115n and 115n+1 is possible to
create overlapped areas between the data lines and the pixel
electrode 120 that are substantially the same. Typically, a width
of a data line used in the liquid crystal display device is
designed to be a minimum width such that a high aperture ratio can
be achieved. However, in the embodiment shown in FIGS. 3A and 3B,
the data lines 115n and 115n+1 protruding into a pixel area to
increase the overlapped areas lowers the aperture ratio. To prevent
the aperture ratio from being lowered the pattern of the pixel
electrode can reconfigured instead of the data lines.
[0039] FIGS. 4A and 4B are plan views showing a pixel of a liquid
crystal display device according to a second embodiment of the
present invention. FIG. 4A shows a pattern of a pixel electrode 220
in a case where area S1 would have been smaller than the area S2
since the width d1 is less than the width d2. As shown in FIG. 4A,
the pixel electrode 220 overlapping data line 215n of a
corresponding pixel area is configured such that a portion of the
pixel electrode 220 protrudes over a portion of a source electrode
232 of a thin film transistor 230 connected to the n.sup.th data
line 215n such that area of overlap for the pixel electrode 20 is
substantially the same for both the 215n and 215n+1 data lines. The
region C in FIG. 4A denotes an increased overlapped area by
configuring the pixel electrode 220 to protrude over the source
electrode 232 of a thin film transistor 230 such that area S1' is
substantially equal to area S2.
[0040] FIG. 4B shows a pattern of the pixel electrode 220 in a case
where the area S1 would have been smaller than the area S2 since
the width d1 is less than the width d2. In FIG. 4B, the overlapped
area above data line 215n+1 is decreased by patterning the pixel
electrode 220 overlapped with a data line 215n+1 of an adjacent
pixel area into a taper shape. The region D in FIG. 4B denotes the
decreased overlapped area of the pixel electrode 220 over the data
line 215n+1 such that area S1 is substantially equal to area
S2'.
[0041] Although, a part of the pixel electrode 220 was patterned
into a taper shape to decrease the overlapped area, any pattern of
pixel electrode 220 can be used if the overlapped areas on the
right and left sides of the pixel area are substantially equal.
Further, if the pixel electrode 220 protrudes over a portion of the
source electrode 232 or the pixel electrode 220 overlaps with the
data line 215n+1 of the adjacent pixel area with a taper shape, as
shown in FIGS. 4A and 4B, the aperture ratio of the liquid crystal
display device is increased.
[0042] FIG. 5 is a plan view showing a pixel of the liquid crystal
display device including a storage capacitor electrode. As shown in
FIG. 5, even if data lines 315n and 315n+1 protrude into the pixel
area above the storage capacitor electrode 525, the aperture ratio
is not decreased. By protruding the data lines 315n and 315n+1 into
the pixel area over the storage capacitor electrode 340 at
intersections between the data lines and the storage electrode 340,
the overlapped areas at the right and left sides of the pixel
electrode are controlled to be substantially equal to one another.
That is, by protruding the right and left data lines 315n and
315n+1 into the pixel area above the storage capacitor electrode
340 and thus varying the area S1 and area S2, a value of the
parasitic capacitance for both of the S1 and S2 areas can be
adjusted to be substantially equivalent. As shown in FIG. 5, region
E denotes the increased overlapped area for the data line 315n of
the corresponding pixel area and region E' denotes the increased
overlapped area for the data line 315n+1 of the adjacent pixel
area. As shown in FIG. 5, since the d1 is less than the d2 and thus
the area S1 is smaller than the area S2, an area of a part 350
protrudes into the corresponding pixel area from the n.sup.th data
line 315n with a length l1 that is larger than an area of a part
355 protruding into the corresponding pixel area from the
n+1.sup.th data line 315n+1n with a length l2. That is, l1 is
longer than l2, so that the overlapped areas of S1' and S2' are
substantially equal.
[0043] FIG. 6 is a plan view showing a pixel of a liquid crystal
display device according to a fourth embodiment of the present
invention in which features of the first embodiment and the second
embodiments in FIGS. 3 and 4 are combined. Since the width d1 is
less than the width d2 in FIG. 6, the area S1 is smaller than the
area S2, a source electrode 432 of a data line 415n of a
corresponding pixel area protrudes under a pixel electrode 420,
thereby increasing area S1' and thus increasing a parasitic
capacitance. In addition, the side of the pixel electrode 420
overlapping data line 415n+1 for an adjacent pixel area is
patterned to have a taper shape such that the area S2' decreases
and the parasitic capacitance associated therewith decreases.
Accordingly, the areas S1' and S2' can be configured to be
substantially equal and have substantially equal parasitic
capacitance. The increase in the area of overlap for the pixel
electrode with the data line 415n is denoted as region F in FIG. 6
and the decrease in the area of overlap for the pixel electrode
with the data line 415n+1 is denoted as region F'.
[0044] In all of the embodiments, the parasitic capacitance
difference can be controlled by configuring the areas S1 and S2 if
permittivity and thickness of the insulator formed between the data
lines and the pixel electrode are substantially fixed. Also, if
said embodiments are performed together with one another, the
parasitic capacitance of right and left sides of the pixel
electrode can be adjusted more flexibly, thereby being able to make
the parasitic capacitance on both sides of the pixel electrode to
be substantially equal.
[0045] As aforementioned, in the present invention, the structures
of the data lines and/or the pixel electrode are changed to make
the parasitic capacitances of both sides of the pixel be equal, so
that light leakage generated at the time of on/off of the switching
device is prevented and thus a picture quality can be improved.
Also, a structure of the present invention can be formed only by
changing the mask without additional processes, so that additional
cost is not required. That is, the present invention can be
performed only by changing the mask pattern at the time of forming
the data lines or the pixel electrode.
[0046] As the present invention may be embodied in several forms
without departing from the spirit or essential characteristics
thereof, it should also be understood that the above-described
embodiments are not limited by any of the details of the foregoing
description, unless otherwise specified, but rather should be
construed broadly within its spirit and scope as defined in the
appended claims, and therefore all changes and modifications that
fall within the metes and bounds of the claims, or equivalence of
such metes and bounds are therefore intended to be embraced by the
appended claims.
* * * * *